[v2,2/4] mips: kdump: Capture kernel should be able to see old memories
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Message ID 1619058274-6996-3-git-send-email-tangyouling@loongson.cn
State New
Headers show
Series
  • mips: Fix related problems in kdump operation
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Commit Message

Youling Tang April 22, 2021, 2:24 a.m. UTC
From: Huacai Chen <chenhc@lemote.com>

kexec-tools use mem=X@Y to pass usable memories to capture kernel, but
in commit a94e4f24ec836c8984f83959 ("MIPS: init: Drop boot_mem_map") all
BIOS passed memories are removed by early_parse_mem(). I think this is
reasonable for a normal kernel but not for a capture kernel, because a
capture kernel should be able to see all old memories, even though it is
not supposed to use them.

Fixes: a94e4f24ec836c8984f83959 ("MIPS: init: Drop boot_mem_map")
Signed-off-by: Huacai Chen <chenhuacai@kernel.org>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
v2:
- Determine whether it is a capture kernel by judging whether there
  is an "elfcorehdr" parameter in the cmdline.

 arch/mips/kernel/setup.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Patch
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diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 9338520..1bc8a9cc 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -352,8 +352,13 @@  static int __init early_parse_mem(char *p)
 	 */
 	if (usermem == 0) {
 		usermem = 1;
-		memblock_remove(memblock_start_of_DRAM(),
-			memblock_end_of_DRAM() - memblock_start_of_DRAM());
+		/*
+		 * During the kdump operation, the old memory should be
+		 * visible to the capture kernel.
+		 */
+		if (!strstr(boot_command_line, "elfcorehdr"))
+			memblock_remove(memblock_start_of_DRAM(),
+				memblock_end_of_DRAM() - memblock_start_of_DRAM());
 	}
 	start = 0;
 	size = memparse(p, &p);